Neutron/openvswitch not working, how to debug

Hello, I'm trying to get Neutron to work, but so far, without any luck.
Basically I have a test setup with two compute nodes, each hosting one instance.
When I log in to one instance, I can't ping the other.

I've tried to trace the network traffic using tcpdump. What I've found is that the ARP requests made by the instance that is attempting to ping do pass through the tapXXXX interface, the int-br0 interface, the phy-br0 interface and then out onto the network via the eth0 interface.

On the other machine, I see the ARP requests coming in via eth0 and br0, but phy-br0 shows now traffic at all. So I think this is the point where it breaks. I just don't have a clue why, or how to further analyze this.